CAMRT Radiography Practice Exam

What is the caudal angle used for anteroposterior axial "inlet" projection of the pelvis?

1. 40-degree caudal angle

2. 30-degree caudal angle

3. 20-degree caudal angle

4. 50-degree caudal angle

The correct answer is: 40-degree caudal angle

The correct choice of a 40-degree caudal angle for the anteroposterior axial "inlet" projection of the pelvis is based on the positioning and anatomical needs for this specific view. The purpose of the caudal angling is to project the pelvic inlet into a better profile, which aids in visualizing the pelvic anatomy, particularly the anterior pelvic structures and the sacrum, while minimizing distortion. When using a 40-degree caudal angle, the X-ray beam is directed downwards towards the feet, facilitating comprehensive imaging of the pelvic inlet. This angle is clinically established for providing an optimal view, allowing radiologists to assess conditions such as pelvic fractures or other abnormalities with greater accuracy. It helps demonstrate the boundaries of the pelvic inlet clearly and helps in evaluating for conditions such as disproportion between the fetal head and the pelvic inlet dimensions in obstetric evaluations. Other angles, like 30-degree, 20-degree, and 50-degree, may not align well with the anatomical structures of interest or may lead to suboptimal imaging where critical details might be obscured or misrepresented. Therefore, the 40-degree caudal angle is recognized as the standard for this projection.